CVE-2026-74635
Description
A flaw was found in the Linux kernel's fbdev subsystem, specifically within the bit_cursor() function. A local user can exploit this vulnerability by writing arbitrary values to the /dev/vcsa device or by manipulating font changes. This improper handling of glyph indices can lead to an out-of-bounds read, potentially resulting in information disclosure or a denial of service.
Statement
This vulnerability is rated as Moderate severity because exploitation requires local access with permissions to manipulate virtual console memory devices or adjust console fonts, restricting the primary impact to a system crash or out-of-bounds memory read. Standard server environments running headless or restricting virtual console device access face significantly lower exposure. Exploitation cannot occur remotely, and the flaw does not facilitate arbitrary code execution.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | 7.8 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | High |
| Integrity Impact | None | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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